body {
    max-width: 540px;
    min-width: 320px;
    margin: 0 auto;
    font: normal 14px/1.5 Tahoma, "Lucida Granda", Verdana, "Microsoft Yahei", STXihei,hei;
    color: #000;
    background-color: #f2f2f2;
    overflow-x: hidden;
    -webkit-tap-highlight-color: transparent;
}
a {
    text-decoration: none;
}
div {
    box-sizing: border-box;
}
/* 搜索模块 */
.search-index {
    display: flex;
    /* 固定定位跟父级没有关系 它以屏幕为准 */
    position: fixed;
    top: 0;
    left: 50%;
    -webkit-transform: translate(-50%);
    transform: translateX(-50%);
    height: 44px;
    width: 100%; 
    max-width: 540px;
    min-width: 320px;
}
.search {
    flex: 1;
    height: 26px;
    border: 1px solid #ccc;
    margin: 7px 10px;
    border-radius: 5px;
}
.user {
    width: 44px;
    height: 44px;
    text-align: center;
    font-size: 12px;
    color: #2eaae0;
}

.user::before {
    display: block;
    content: '';
    width: 23px;
    height: 23px;
    margin: 2px auto 0;
    background: url(../images/sprite.png) no-repeat -58px -192px;
    background-size: 104px auto;
}